Leap year

A leap year (also known as an intercalary year or bissextile year) is a calendar year containing one additional day (or, in the case of lunisolar calendars, a month) added to keep the calendar year synchronized with the astronomical or seasonal year.[1] Because seasons and astronomical events do not repeat in a whole number of days, calendars that have the same number of days in each year drift over time with respect to the event that the year is supposed to track. By inserting (also called intercalating) an additional day or month into the year, the drift can be corrected. A year that is not a leap year is called a common year.

For example, in the Gregorian calendar, each leap year has 366 days instead of the usual 365, by extending February to 29 days rather than the common 28. These extra days occur in years which are multiples of four (with the exception of years divisible by 100 but not by 400). Similarly, in the lunisolar Hebrew calendar, Adar Aleph, a 13th lunar month, is added seven times every 19 years to the twelve lunar months in its common years to keep its calendar year from drifting through the seasons. In the Bahá'í Calendar, a leap day is added when needed to ensure that the following year begins on the vernal equinox.

The name "leap year" probably comes from the fact that while a fixed date in the Gregorian calendar normally advances one day of the week from one year to the next, the day of the week in the 12 months following the leap day (from March 1 through February 28 of the following year) will advance two days due to the extra day (thus "leaping over" one of the days in the week).[2][3] For example, Christmas Day (December 25) fell on a Monday in 2017, then it will fall on Tuesday in 2018, and Wednesday in 2019 but then "leaps" over Thursday to fall on a Friday in 2020.

The length of a day is also occasionally changed by the insertion of leap seconds into Coordinated Universal Time (UTC), owing to the variability of Earth's rotational period. Unlike leap days, leap seconds are not introduced on a regular schedule, since the variability in the length of the day is not entirely predictable.

An image showing which century years are leap years in the Gregorian calendar.

In the Gregorian calendar, the standard calendar in most of the world, most years that are multiples of 4 are leap years. In each leap year, the month of February has 29 days instead of 28. Adding one extra day in the calendar every four years compensates for the fact that a period of 365 days is shorter than a tropical year by almost 6 hours.[4] Some exceptions to this basic rule are required since the duration of a tropical year is slightly less than 365.25 days. The Gregorian reform modified the Julian calendar's scheme of leap years as follows:

Every year that is exactly divisible by four is a leap year, except for years that are exactly divisible by 100, but these centurial years are leap years if they are exactly divisible by 400. For example, the years 1700, 1800, and 1900 were not leap years, but the years 1600 and 2000 were.[5]

Over a period of four centuries, the accumulated error of adding a leap day every four years amounts to about three extra days. The Gregorian calendar therefore removes three leap days every 400 years, which is the length of its leap cycle. This is done by removing February 29 in the three century years (multiples of 100) that cannot be exactly divided by 400.[6][7] The years 1600, 2000 and 2400 are leap years, while 1700, 1800, 1900, 2100, 2200 and 2300 are common years. By this rule, the average number of days per year is 365 + ​1⁄4 − ​1⁄100 + ​1⁄400 = 365.2425.[8] The rule can be applied to years before the Gregorian reform (the proleptic Gregorian calendar), if astronomical year numbering is used.[9]

This graph shows the variations in date and time of the June Solstice due to unequally spaced "leap day" rules. Contrast this with the Iranian Solar Hijri calendar, which generally has 8 leap year days every 33 years.

The Gregorian calendar was designed to keep the vernal equinox on or close to March 21, so that the date of Easter (celebrated on the Sunday after the ecclesiastical full moon that falls on or after March 21) remains close to the vernal equinox.[10][8] The "Accuracy" section of the "Gregorian calendar" article discusses how well the Gregorian calendar achieves this design goal, and how well it approximates the tropical year.

The following pseudocode determines whether a year is a leap year or a common year in the Gregorian calendar (and in the proleptic Gregorian calendar before 1582). The year variable being tested is the integer representing the number of the year in the Gregorian calendar, and the tests are arranged to dispatch the most common cases first. Care should be taken in translating mathematical integer divisibility into specific programming languages.

if (year is not divisible by 4) then (it is a common year)else if (year is not divisible by 100) then (it is a leap year)else if (year is not divisible by 400) then (it is a common year)else (it is a leap year)

The algorithm applies to proleptic Gregorian calendar years before 1, but only if the year is expressed with astronomical year numbering. It is not valid for the BC or BCE notation. The algorithm is not necessarily valid for years in the Julian calendar, such as years before 1752 in the British Empire. The year 1700 was a leap year in the Julian calendar, but not in the Gregorian calendar.

February 29 is a date that usually occurs every four years, and is called leap day. This day is added to the calendar in leap years as a corrective measure, because the Earth does not orbit the sun in precisely 365 days.

The Gregorian calendar is a modification of the Julian calendar first used by the Romans. The Roman calendar originated as a lunisolar calendar and named many of its days after the syzygies of the moon: the new moon (Kalendae or calends, hence "calendar") and the full moon (Idus or ides). The Nonae or nones was not the first quarter moon but was exactly one nundina or Roman market week of nine days before the ides, inclusively counting the ides as the first of those nine days. This is what we would call a period of eight days. In 1825, Ideler believed that the lunisolar calendar was abandoned about 450 BC by the decemvirs, who implemented the Roman Republican calendar, used until 46 BC. The days of these calendars were counted down (inclusively) to the next named day, so February 24 was ante diem sextum Kalendas Martias ("the sixth day before the calends of March") often abbreviated a. d. VI Kal. Mart. The Romans counted days inclusively in their calendars, so this was actually the fifth day before March 1 when counted in the modern exclusive manner (not including the starting day).[11]

The Republican calendar's intercalary month was inserted on the first or second day after the Terminalia (a. d. VII Kal. Mar., February 23). The remaining days of Februarius were dropped. This intercalary month, named Intercalaris or Mercedonius, contained 27 days. The religious festivals that were normally celebrated in the last five days of February were moved to the last five days of Intercalaris. Because only 22 or 23 days were effectively added, not a full lunation, the calends and ides of the Roman Republican calendar were no longer associated with the new moon and full moon.

The Julian calendar, which was developed in 46 BC by Julius Caesar, and became effective in 45 BC, distributed an extra ten days among the months of the Roman Republican calendar. Caesar also replaced the intercalary month by a single intercalary day, located where the intercalary month used to be. To create the intercalary day, the existing ante diem sextum Kalendas Martias (February 24) was doubled, producing ante diem bis sextum Kalendas Martias. Hence, the year containing the doubled day was a bissextile (bis sextum, "twice sixth") year. For legal purposes, the two days of the bis sextum were considered to be a single day, with the second half being intercalated; but in common practice by 238, when Censorinus wrote, the intercalary day was followed by the last five days of February, a. d. VI, V, IV, III and pridie Kal. Mart. (the days numbered 24, 25, 26, 27, and 28 from the beginning of February in a common year), so that the intercalated day was the first half of the doubled day. Thus the intercalated day was effectively inserted between the 23rd and 24th days of February. All later writers, including Macrobius about 430, Bede in 725, and other medieval computists (calculators of Easter), continued to state that the bissextum (bissextile day) occurred before the last five days of February.

In the older Roman Missal, feast days falling on or after February 24 are celebrated one day later in leap year.

Until 1970, the Roman Catholic Church always celebrated the feast of Saint Matthias on a. d. VI Kal. Mart., so if the days were numbered from the beginning of the month, it was named February 24 in common years, but the presence of the bissextum in a bissextile year immediately before a. d. VI Kal. Mart. shifted the latter day to February 25 in leap years, with the Vigil of St. Matthias shifting from February 23 to the leap day of February 24. This shift did not take place in pre-Reformation Norway and Iceland; Pope Alexander III ruled that either practice was lawful (Liber Extra, 5. 40. 14. 1). Other feasts normally falling on February 25–28 in common years are also shifted to the following day in a leap year (although they would be on the same day according to the Roman notation). The practice is still observed by those who use the older calendars.

The Revised Bengali Calendar of Bangladesh and the Indian National Calendar organise their leap years so that the every leap day is close to a February 29 in the Gregorian calendar and vice versa. This makes it easy to convert dates to or from Gregorian.

This rule gives an average year length of 365.25 days. However, it is 11 minutes longer than a tropical year. This means that the vernal equinox moves a day earlier in the calendar about every 131 years.

The Revised Julian calendar adds an extra day to February in years that are multiples of four, except for years that are multiples of 100 that do not leave a remainder of 200 or 600 when divided by 900. This rule agrees with the rule for the Gregorian calendar until 2799. The first year that dates in the Revised Julian calendar will not agree with those in the Gregorian calendar will be 2800, because it will be a leap year in the Gregorian calendar but not in the Revised Julian calendar.

This rule gives an average year length of 365.242222 days. This is a very good approximation to the mean tropical year, but because the vernal equinox year is slightly longer, the Revised Julian calendar for the time being does not do as good a job as the Gregorian calendar at keeping the vernal equinox on or close to March 21.

The Chinese calendar is lunisolar, so a leap year has an extra month, often called an embolismic month after the Greek word for it. In the Chinese calendar the leap month is added according to a rule which ensures that month 11 is always the month that contains the northern winter solstice. The intercalary month takes the same number as the preceding month; for example, if it follows the second month (二月) then it is simply called "leap second month" i.e. simplified Chinese: 闰二月; traditional Chinese: 閏二月; pinyin: rùn'èryuè.

The Hebrew calendar is lunisolar with an embolismic month. This extra month is called Adar Alef (first Adar) and is added before Adar, which then becomes Adar Bet (second Adar). According to the Metonic cycle, this is done seven times every nineteen years (specifically, in years 3, 6, 8, 11, 14, 17, and 19). This is to ensure that Passover (Pesah) is always in the spring as required by the Torah (Pentateuch) in many verses[12] relating to Passover.

In addition, the Hebrew calendar has postponement rules that postpone the start of the year by one or two days. These postponement rules reduce the number of different combinations of year length and starting days of the week from 28 to 14, and regulate the location of certain religious holidays in relation to the Sabbath. In particular, the first day of the Hebrew year can never be Sunday, Wednesday or Friday. This rule is known in Hebrew as "lo adu rosh" (לא אד"ו ראש), i.e., "Rosh [ha-Shanah, first day of the year] is not Sunday, Wednesday or Friday" (as the Hebrew word adu is written by three Hebrew letters signifying Sunday, Wednesday and Friday). Accordingly, the first day of Passover is never Monday, Wednesday or Friday. This rule is known in Hebrew as "lo badu Pesah" (לא בד"ו פסח), which has a double meaning — "Passover is not a legend", but also "Passover is not Monday, Wednesday or Friday" (as the Hebrew word badu is written by three Hebrew letters signifying Monday, Wednesday and Friday).

One reason for this rule is that Yom Kippur, the holiest day in the Hebrew calendar and the tenth day of the Hebrew year, now must never be adjacent to the weekly Sabbath (which is Saturday), i.e., it must never fall on Friday or Sunday, in order not to have two adjacent Sabbath days. However, Yom Kippur can still be on Saturday. These rules for the Feasts do not apply to the years from the Creation to the deliverance of the Hebrews from Egypt under Moses. It was at that time (cf. Exodus 13) that the God of Abraham, Isaac and Jacob gave the Hebrews their "Law" including the days to be kept holy and the feast days and Sabbaths.

Years consisting of 12 months have between 353 and 355 days. In a k'sidra ("in order") 354-day year, months have alternating 30 and 29 day lengths. In a chaser ("lacking") year, the month of Kislev is reduced to 29 days. In a malei ("filled") year, the month of Marcheshvan is increased to 30 days. 13-month years follow the same pattern, with the addition of the 30-day Adar Alef, giving them between 383 and 385 days.

The observed and calculated versions of the Islamic calendar do not have regular leap days, even though both have lunar months containing 29 or 30 days, generally in alternating order. However, the tabular Islamic calendar used by Islamic astronomers during the Middle Ages and still used by some Muslims does have a regular leap day added to the last month of the lunar year in 11 years of a 30-year cycle.[13] This additional day is found at the end of the last month, Dhu 'l-Hijja, which is also the month of the Hajj.[14]

The Hijri-Shamsi calendar, also adopted by the Ahmadiyya Muslim Community, is based on solar calculations and is similar to the Gregorian calendar in its structure with the exception that the first year starts with Hijra.[15]

In the Hindu calendar, which is a lunisolar calendar, the embolismic month is called adhika maas (extra month). It is the month in which the sun is in the same sign of the stellar zodiac on two consecutive dark moons. Adhika maas occurs once every 33 to 34 months, compensating for the approximately eleven fewer days per year in twelve lunar months than the solar calendar. Thus, Hindu festivals tend to occur within a given span of the Gregorian calendar. For example: the No Moon during Diwali festival occurs between mid - October and mid - November. Buddhist calendars in several related forms (each a simplified version of the Hindu calendar) are used on mainland Southeast Asia in the countries of Cambodia, Laos, Thailand, Myanmar (formerly Burma) and Sri Lanka.

The Hindu Calendar also known as Vikram Samvat is used in Nepal as the national calendar. All the official work is done based on this calendar.

The Bahá'í calendar is a solar calendar composed of 19 months of 19 days each (361 days). Years begin at Naw-Rúz, on the vernal equinox, on or about March 21. A period of "Intercalary Days", called Ayyam-i-Ha, are inserted before the 19th month. This period normally has 4 days, but an extra day is added when needed to ensure that the following year starts on the vernal equinox. This is calculated and known years in advance.

The Iranian calendar is an observational calendar that starts on the spring equinox and adds a single intercalated day to the last month (Esfand) once every four or five years; the first leap year occurs as the fifth year of the typical 33-year cycle and the remaining leap years occur every four years through the remainder of the 33-year cycle. The system used is more accurate and more complicated, and is based on the time of the March equinox as observed from Tehran. The 33-year period is not completely regular; every so often the 33-year cycle will be broken by a cycle of 29 years.
[16]

In Ireland and Britain, it is a tradition that women may propose marriage only in leap years. While it has been claimed that the tradition was initiated by Saint Patrick or Brigid of Kildare in 5th century Ireland, this is dubious, as the tradition has not been attested before the 19th century.[17] Supposedly, a 1288 law by Queen Margaret of Scotland (then age five and living in Norway), required that fines be levied if a marriage proposal was refused by the man; compensation was deemed to be a pair of leather gloves, a single rose, £1 and a kiss.[18] In some places the tradition was tightened to restricting female proposals to the modern leap day, February 29, or to the medieval (bissextile) leap day, February 24.

According to Felten: "A play from the turn of the 17th century, 'The Maydes Metamorphosis,' has it that 'this is leape year/women wear breeches.' A few hundred years later, breeches wouldn't do at all: Women looking to take advantage of their opportunity to pitch woo were expected to wear a scarlet petticoat — fair warning, if you will."[19]

In Finland, the tradition is that if a man refuses a woman's proposal on leap day, he should buy her the fabrics for a skirt.[20]

In France, since 1980, a satirical newspaper entitled La Bougie du Sapeur is published only on leap year, on February 29.

In Greece, marriage in a leap year is considered unlucky.[21] One in five engaged couples in Greece will plan to avoid getting married in a leap year.[22]

In February 1988 the town of Anthony in Texas, declared itself "leap year capital of the world", and an international leapling birthday club was started.[23]

A person born on February 29 may be called a "leapling" or a "leaper".[24] In common years, they usually celebrate their birthdays on February 28. In some situations, March 1 is used as the birthday in a non-leap year, since it is the day following February 28.

Technically, a leapling will have fewer birthday anniversaries than their age in years. This phenomenon is exploited when a person claims to be only a quarter of their actual age, by counting their leap-year birthday anniversaries only. In Gilbert and Sullivan's 1879 comic operaThe Pirates of Penzance, Frederic the pirate apprentice discovers that he is bound to serve the pirates until his 21st birthday (that is, when he turns 88 years old - 1900 not being a Leap Year), rather than until his 21st year.

For legal purposes, legal birthdays depend on how local laws count time intervals.

The Civil Code of the Republic of China since October 10, 1929,[25] implies that the legal birthday of a leapling is February 28 in common years:

If a period fixed by weeks, months, and years does not commence from the beginning of a week, month, or year, it ends with the ending of the day which precedes the day of the last week, month, or year which corresponds to that on which it began to commence. But if there is no corresponding day in the last month, the period ends with the ending of the last day of the last month.[26]

^Virtually no laws of Margaret survive. Indeed, none concerning her subjects are recorded in the twelve volume Acts of the Parliaments of Scotland (1814–75) covering the period 1124–1707 (two laws concerning young Margaret herself are recorded on pages 424 & 441–2 of volume I).

1.
Lunisolar calendar
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A lunisolar calendar is a calendar in many cultures whose date indicates both the moon phase and the time of the solar year. As with all calendars which divide the year into months there is a requirement that the year have a whole number of months. In this case ordinary years consist of twelve months but every second or third year is an embolismic year, also, some of the ancient pre-Islamic calendars in south Arabia followed a lunisolar system. The Chinese, Coligny and Hebrew lunisolar calendars track more or less the tropical year whereas the Buddhist, therefore, the first three give an idea of the seasons whereas the last two give an idea of the position among the constellations of the full moon. The Tibetan calendar was influenced by both the Chinese and Hindu calendars, the Germanic peoples also used a lunisolar calendar before their conversion to Christianity. The Metonic cycle, used in the Hebrew calendar and the Julian and Gregorian ecclesiastical calendars, the classic Metonic cycle can be reproduced by assigning an initial epact value of 1 to the last year of the cycle and incrementing by 11 each year. Between the last year of one cycle and the first year of the next the increment is 12 and this adjustment, the saltus lunae, causes the epacts to repeat every 19 years. When the epact goes above 29 an intercalary month is added and 30 is subtracted, the intercalary years are numbers 3,6,8,11,14,17 and 19. Both the Hebrew calendar and the Julian calendar use this sequence, the Buddhist and Hebrew calendars restrict the leap month to a single month of the year, the number of common months between leap months is, therefore, usually 36, but occasionally only 24 months. An alternative way of dealing with the fact that a year does not contain an integer number of months is by including uncounted time in the year that does not belong to any month. Some Coast Salish peoples used a calendar of this kind, for instance, the Chehalis began their count of lunar months from the arrival of spawning chinook salmon, and counted 10 months, leaving an uncounted period until the next chinook salmon run. The Gregorian calendar has a calendar, which is used to determine the date of Easter. The rules are in the Computus, Hebrew calendar Jain calendar Hindu calendar Computus Easter rule for Julian and Gregorian calendars. Lunisolar calendar year 2014 Lunisolar Calendar Calendar studies Model of lunisolar calendar based on observation of the sun and moon position

2.
Astronomical year
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A year is the orbital period of the Earth moving in its orbit around the Sun. Due to the Earths axial tilt, the course of a year sees the passing of the seasons, marked by changes in weather, the hours of daylight, and, consequently, vegetation and soil fertility. In temperate and subpolar regions around the globe, four seasons are recognized, spring, summer, autumn. In tropical and subtropical regions several geographical sectors do not present defined seasons, but in the seasonal tropics, a calendar year is an approximation of the number of days of the Earths orbital period as counted in a given calendar. The Gregorian, or modern, calendar, presents its calendar year to be either a common year of 365 days or a year of 366 days, as do the Julian calendars. For the Gregorian calendar the average length of the year across the complete leap cycle of 400 years is 365.2425 days. The ISO standard ISO 80000-3, Annex C, supports the symbol a to represent a year of either 365 or 366 days, in English, the abbreviations y and yr are commonly used. In astronomy, the Julian year is a unit of time, it is defined as 365.25 days of exactly 86400 seconds, totalling exactly 31557600 seconds in the Julian astronomical year. The word year is used for periods loosely associated with, but not identical to, the calendar or astronomical year, such as the seasonal year, the fiscal year. Similarly, year can mean the period of any planet, for example. The term can also be used in reference to any long period or cycle, west Saxon ġēar, Anglian ġēr continues Proto-Germanic *jǣran. Cognates are German Jahr, Old High German jār, Old Norse ár and Gothic jer, all the descendants of the Proto-Indo-European noun *yeh₁rom year, season. Cognates also descended from the same Proto-Indo-European noun are Avestan yārǝ year, Greek ὥρα year, season, period of time, Old Church Slavonic jarŭ, Latin annus is from a PIE noun *h₂et-no-, which also yielded Gothic aþn year. Both *yeh₁-ro- and *h₂et-no- are based on verbal roots expressing movement, *h₁ey- and *h₂et- respectively, the Greek word for year, ἔτος, is cognate with Latin vetus old, from the PIE word *wetos- year, also preserved in this meaning in Sanskrit vat-sa- yearling and vat-sa-ras year. Derived from Latin annus are a number of English words, such as annual, annuity, anniversary, etc. per annum means each year, anno Domini means in the year of the Lord. No astronomical year has an number of days or lunar months. Financial and scientific calculations often use a 365-day calendar to simplify daily rates, in the Julian calendar, the average length of a year is 365.25 days. In a non-leap year, there are 365 days, in a year there are 366 days

3.
Natural number
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In mathematics, the natural numbers are those used for counting and ordering. In common language, words used for counting are cardinal numbers, texts that exclude zero from the natural numbers sometimes refer to the natural numbers together with zero as the whole numbers, but in other writings, that term is used instead for the integers. These chains of extensions make the natural numbers canonically embedded in the number systems. Properties of the numbers, such as divisibility and the distribution of prime numbers, are studied in number theory. Problems concerning counting and ordering, such as partitioning and enumerations, are studied in combinatorics, the most primitive method of representing a natural number is to put down a mark for each object. Later, a set of objects could be tested for equality, excess or shortage, by striking out a mark, the first major advance in abstraction was the use of numerals to represent numbers. This allowed systems to be developed for recording large numbers, the ancient Egyptians developed a powerful system of numerals with distinct hieroglyphs for 1,10, and all the powers of 10 up to over 1 million. A stone carving from Karnak, dating from around 1500 BC and now at the Louvre in Paris, depicts 276 as 2 hundreds,7 tens, and 6 ones, and similarly for the number 4,622. A much later advance was the development of the idea that 0 can be considered as a number, with its own numeral. The use of a 0 digit in place-value notation dates back as early as 700 BC by the Babylonians, the Olmec and Maya civilizations used 0 as a separate number as early as the 1st century BC, but this usage did not spread beyond Mesoamerica. The use of a numeral 0 in modern times originated with the Indian mathematician Brahmagupta in 628, the first systematic study of numbers as abstractions is usually credited to the Greek philosophers Pythagoras and Archimedes. Some Greek mathematicians treated the number 1 differently than larger numbers, independent studies also occurred at around the same time in India, China, and Mesoamerica. In 19th century Europe, there was mathematical and philosophical discussion about the nature of the natural numbers. A school of Naturalism stated that the numbers were a direct consequence of the human psyche. Henri Poincaré was one of its advocates, as was Leopold Kronecker who summarized God made the integers, in opposition to the Naturalists, the constructivists saw a need to improve the logical rigor in the foundations of mathematics. In the 1860s, Hermann Grassmann suggested a recursive definition for natural numbers thus stating they were not really natural, later, two classes of such formal definitions were constructed, later, they were shown to be equivalent in most practical applications. The second class of definitions was introduced by Giuseppe Peano and is now called Peano arithmetic and it is based on an axiomatization of the properties of ordinal numbers, each natural number has a successor and every non-zero natural number has a unique predecessor. Peano arithmetic is equiconsistent with several systems of set theory

4.
Intercalation (timekeeping)
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Intercalation or embolism in timekeeping is the insertion of a leap day, week, or month into some calendar years to make the calendar follow the seasons or moon phases. Lunisolar calendars may require intercalations of both days and months, the solar or tropical year does not have a whole number of days, but a calendar year must have a whole number of days. The most common way to reconcile the two is to vary the number of days in the calendar year. In solar calendars, this is done by adding to a year of 365 days. In the Julian calendar, as well as in the Gregorian calendar, in the Julian calendar this was done every four years. In the Gregorian, years divisible by 100 but not 400 were exempted in order to improve accuracy, thus,2000 was a leap year,1700,1800, and 1900 were not. Epagomenal days are days within a calendar that are outside any regular month. Usually five epagomenal days are included within every year, but a sixth day is intercalated every four years in some. The Baháí calendar includes enough epagomenal days before the last month to ensure that the year starts on the March equinox. These are known as the Ayyám-i-Há, the solar year does not have a whole number of lunar months, so a lunisolar calendar must have a variable number of months in a year. Regular years have 12 months, but embolismic years insert a 13th intercalary or embolismic month every second or third year, whether to insert an intercalary month in a given year may be determined using regular cycles such as the 19-year Metonic cycle or using calculations of lunar phases. The Buddhist calendar adds both a day and month on a usually regular cycle. Some historians also linked the practice of Nasi to intercalation. The International Earth Rotation and Reference Systems Service can insert or remove leap seconds from the last day of any month and these are sometimes described as intercalary. ISO8601 includes a specification for a 52-week year, any year that has 53 Thursdays has 53 weeks, this extra week may be regarded as intercalary

5.
Gregorian calendar
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The Gregorian calendar is internationally the most widely used civil calendar. It is named after Pope Gregory XIII, who introduced it in October 1582, the calendar was a refinement to the Julian calendar involving a 0. 002% correction in the length of the year. The motivation for the reform was to stop the drift of the calendar with respect to the equinoxes and solstices—particularly the northern vernal equinox, transition to the Gregorian calendar would restore the holiday to the time of the year in which it was celebrated when introduced by the early Church. The reform was adopted initially by the Catholic countries of Europe, the last European country to adopt the reform was Greece, in 1923. Many countries that have used the Islamic and other religious calendars have come to adopt this calendar for civil purposes. The reform was a modification of a made by Aloysius Lilius. His proposal included reducing the number of years in four centuries from 100 to 97. Lilius also produced an original and practical scheme for adjusting the epacts of the moon when calculating the date of Easter. For example, the years 1700,1800, and 1900 are not leap years, but the years 1600 and 2000 are. The canonical Easter tables were devised at the end of the third century, when the vernal equinox fell either on 20 March or 21 March depending on the years position in the leap year cycle. As the rule was that the full moon preceding Easter was not to precede the equinox, the date was fixed at 21 March for computational purposes, the Gregorian calendar reproduced these conditions by removing ten days. To unambiguously specify a date, dual dating or Old Style, dual dating gives two consecutive years for a given date, because of differences in the starting date of the year, and/or to give both the Julian and the Gregorian dates. The Gregorian calendar continued to use the calendar era, which counts years from the traditional date of the nativity. This year-numbering system, also known as Dionysian era or Common Era, is the predominant international standard today, the Gregorian calendar is a solar calendar. A regular Gregorian year consists of 365 days, but as in the Julian calendar, in a leap year, in the Julian calendar a leap year occurs every 4 years, but the Gregorian calendar omits 3 leap days every 400 years. In the Julian calendar, this day was inserted by doubling 24 February. In the modern period, it has become customary to number the days from the beginning of the month, some churches, notably the Roman Catholic Church, delay February festivals after the 23rd by one day in leap years. Gregorian years are identified by consecutive year numbers, the cycles repeat completely every 146,097 days, which equals 400 years

6.
February 29
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February 29, also known as leap day or leap year day, is a date added to most years that are divisible by 4, such as 2008,2012,2016,2020, and 2024. A leap day is added in various solar calendars, including the Gregorian calendar standard in most of the world, lunisolar calendars instead add a leap or intercalary month. In the Gregorian calendar, years that are divisible by 100, thus,1700,1800, and 1900 did not contain a leap day, neither will 2100,2200, and 2300. Conversely,1600 and 2000 did and 2400 will, Years containing a leap day are called leap years. Years not containing a leap day are called common years, February 29 is the 60th day of the Gregorian calendar, in such a year, with 306 days remaining until the end of the year. In the Chinese calendar, this day will only occur in years of the monkey, dragon, a leap day is observed because a complete revolution around the Sun takes approximately 6 hours longer than 365 days. A leap day compensates for this lag, realigning the calendar with the Earths position in the Solar System, otherwise, although most modern calendar years have 365 days, a complete revolution around the Sun takes approximately 365 days and 6 hours. An extra 24 hours thus accumulates every four years, requiring that a calendar day be added to align the calendar with the Suns apparent position. A solar year is slightly shorter than 365 days and 6 hours. The currently accepted figure is 365 days,5 hours,48 minutes,45 seconds. Adding a calendar day every four years, therefore, results in an excess of around 44 minutes for those four years, to compensate for this, three days are removed every 400 years. The Gregorian calendar reform implements this adjustment by making an exception to the rule that there is a leap year every four years. Instead, a year divisible by 100 is not a year unless that year is also divisible by 400. This means that the years 1600,2000, and 2400 are leap years, while the years 1700,1800,1900,2100,2200,2300, the Gregorian calendar repeats itself every 400 years, which is exactly 20,871 weeks including 97 leap days. Over this period, February 29 falls on Sunday, Tuesday, and Thursday 13 times each,14 times each on Friday and Saturday, the calendar of the Roman king Numa Pompilius had only 355 days which meant that it would quickly become unsynchronized with the solar year. An earlier Roman solution to this problem was to lengthen the calendar periodically by adding days to February. February consisted of two parts, each with an odd number of days, the first part ended with the Terminalia on the 23rd, which was considered the end of the religious year, and the five remaining days formed the second part. To keep the calendar year roughly aligned with the solar year, the second part of February was incorporated in the intercalary month as its last five days, with no change either in their dates or the festivals observed on them

7.
Hebrew calendar
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The Hebrew or Jewish calendar is a lunisolar calendar used today predominantly for Jewish religious observances. It determines the dates for Jewish holidays and the public reading of Torah portions, yahrzeits. The present Hebrew calendar is the product of evolution, including a Babylonian influence, when to add it was based on observation of natural agriculture-related events in Israel. Through the Amoraic period and into the Geonic period, this system was displaced by the mathematical rules used today. The principles and rules were codified by Maimonides in the Mishneh Torah in the 12th century. Maimonides work also replaced counting years since the destruction of the Temple with the modern creation-era Anno Mundi, the era used since the Middle Ages is the Anno Mundi epoch. As with Anno Domini, the words or abbreviation for Anno Mundi for the era should properly precede the date rather than follow it, AM5777 began at sunset on 2 October 2016 and will end at sunset on 20 September 2017. The Jewish day is of no fixed length, the Jewish day is modeled on the reference to. there was evening and there was morning. In the creation account in the first chapter of Genesis, based on the classic rabbinic interpretation of this text, a day in the rabbinic Hebrew calendar runs from sunset to the next sunset. In most populated parts of the world this is always approximately 24 standard hours, halachically, a day ends and a new one starts when three stars are visible in the sky. The time between sunset and the time when the three stars are visible is known as bein hashmashot, and there are differences of opinion as to which day it falls into for some uses. This may be relevant, for example, in determining the date of birth of a child born during that gap, there is no clock in the Jewish scheme, so that the local civil clock is used. The civil clock is used only as a reference point – in expressions such as, Shabbat starts at. In Judaism, an hour is defined as 1/12 of the time from sunrise to sunset, so, during the winter, an hour can be less than 60 minutes. This proportional hour is known as a shaah zmanit, a Jewish hour is divided into 1080 halakim or parts. A part is 3⅓ seconds or 1/18 minute, the ultimate ancestor of the helek was a small Babylonian time period called a barleycorn, itself equal to 1/72 of a Babylonian time degree. These measures are not generally used for everyday purposes, instead of the international date line convention, there are varying opinions as to where the day changes. One opinion uses the antimeridian of Jerusalem, the weekdays start with Sunday and proceed to Saturday, Shabbat

8.
Adar
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Adar is the sixth month of the civil year and the twelfth month of the ecclesiastical year on the Hebrew calendar. It is a month of 29 days. The Month of Adar in the Holy Scriptures comprises in Esther 09,21, in leap years, it is preceded by a 30-day intercalary month named Adar Aleph and it is then itself called Adar Bet. Occasionally instead of Adar I and Adar II, Adar and VeAdar are used, Adar I and II occur during February–March on the Gregorian calendar. Based on a line in the Mishnah declaring that Purim must be celebrated in Adar II in a year, Adar I is considered the extra month. As a result, someone born in Adar during a non leap year would celebrate his birthday in Adar II during a leap year and this started on the 1st of Adar, six weeks before the Exodus. 1 Adar - Death of the Ibn Ezra 1 Adar - Death of the Shach 2 Adar - Jerusalem falls to Nebuchadnezzar,3 Adar - Second Temple completed 4 Adar - Maharams body ransomed 14 years after his death by Alexander ben Shlomo Wimpfen. 4 Adar - Death of Rabbi Leib Sarahs, a disciple of the Rabbi Israel Baal Shem Tov, one of the hidden tzaddikim, Rabbi Leib spent his life wandering from place to place to raise money for the ransoming of imprisoned Jews and the support of other hidden tzaddikim. 5 Adar - Lulianos and Pappos voluntarily gave themselves up to be killed,7 Adar - Birth of Moses 7 Adar - Death of Moses 7 Adar - Death of Rebbe Isaac Taub of Kalov, founder of the Kalover Hasidic dynasty, and a student of Rabbi Leib Sarahs. 9 Adar - Academic dissension between Beit Hillel and Beit Shammai, erupted into a violent and destructive conflict over a vote on 18 legal matters leading to the death of 3,000 students. The day was declared a fast day by the Shulchan Aruch, however. 11 Adar - Death of Reb Eliezer Lipman, father of the prominent Chassidic Rebbes Rabbi Elimelech of Lizhensk,13 Adar - War between Jews and their enemies in Persia. 13 Adar - Yom Nicanor - The Maccabees defeated Syrian general Nicanor, in a battle fought four years after the Maccabees liberation of the Holy Land and the miracle of Hanukkah. The day was established as a community Purim for generations and to day the Washington Heights community does not recite Tachanun on this day. 20 Adar - Death of the Bach 21 Adar - Death of Rabbi Elimelech of Lizhensk 23 Adar - Mishkan assembled for the first time, Seven Days of Training begin. 23 Adar - Death of Yitzchak Meir Alter, first Rebbe of Ger 24 Adar - The Blood Libel, nevertheless, nearly a hundred years later the accusation was officially leveled against Mendel Beilis in Kiev. 25 Adar - Death of Nebuchadnezzar,25 Adar - Death of Rabbi Abraham Gershon of Kitov the brother-in-law and leading foe-turned-disciple of the Baal Shem Tov.27 Adar - Death of Zedekiah in Babylonian captivity. Meroduch, Nebuchadnezzars son and successor, freed him on the 27th of Adar,28 Adar - Talmudic holiday to commemorate the rescinding of a Roman decree against Torah study, ritual circumcision, and keeping the Shabbat

9.
March equinox
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In the Northern Hemisphere the March equinox is known as the vernal equinox, and in the Southern Hemisphere as the autumnal equinox. On the Gregorian calendar the Northward equinox can occur as early as 19 March or as late as 21 March. For a common year the computed time slippage is about 5 hours 49 minutes later than the previous year, and for a leap year about 18 hours 11 minutes earlier than the previous year. Balancing the increases of the years against the losses of the leap years keeps the calendar date of the March equinox from drifting more than one day from 20 March each year. The March equinox may be taken to mark the beginning of spring and the end of winter in the Northern Hemisphere but marks the beginning of autumn, in astronomy, the March equinox is the zero point of sidereal time and, consequently, right ascension. It also serves as a reference for calendars and celebrations in many human cultures, the March equinox is one point in time commonly used to determine the length of the tropical year. The mean tropical year is the average of all the tropical years measured from every point along the Earths orbit. The following table shows the small variations in timing over a period of time. The point where the Sun crosses the equator northwards is called the First Point of Aries. However, due to the precession of the equinoxes, this point is no longer in the constellation Aries, by the year 2600 it will be in Aquarius. The Earths axis causes the First Point of Aries to travel westwards across the sky at a rate of one degree every 72 years. It passed by a corner of Cetus at 0°10′ distance in the year 1489. In its apparent motion on the day of an equinox, the Suns disk crosses the Earths horizon directly to the east at dawn—rising, the March equinox, like all equinoxes, is characterized by having an almost exactly equal amount of daylight and night across most latitudes on Earth. Due to refraction of light rays in the Earths atmosphere the Sun will be visible above the horizon even when its disc is completely below the limb of the Earth and these conditions produce differentials of actual durations of light and darkness at various locations on Earth during an equinox. This is most notable at the extreme latitudes, where the Sun may be seen to travel sideways considerably during the dawn. The Persian calendar begins each year at the equinox, observationally determined at Tehran. The Indian national calendar starts the year on the day next to the equinox on 22 March with a 30-day month. The Julian calendar reform lengthened seven months and replaced the intercalary month with a day to be added every four years to February

10.
Christmas
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In several countries, celebrating Christmas Eve on December 24 has the main focus rather than December 25, with gift-giving and sharing a traditional meal with the family. Although the month and date of Jesus birth are unknown, by the fourth century the Western Christian Church had placed Christmas on December 25. Today, most Christians celebrate on December 25 in the Gregorian calendar and this is not a disagreement over the date of Christmas as such, but rather a preference of which calendar should be used to determine the day that is December 25. Although it is not known why December 25 became a date of celebration, December 25 was the date the Romans marked as the winter solstice, the shortest, and therefore darkest day of the year. Jesus was identified with the Sun based on an Old Testament verse, the date is exactly nine months following Annunciation, when the conception of Jesus is celebrated. Finally, the Romans had a series of pagan festivals near the end of the year, so Christmas may have been scheduled at this time to appropriate, or compete with, one or more of these festivals. The celebratory customs associated in various countries with Christmas have a mix of pre-Christian, Christian, the economic impact of Christmas has grown steadily over the past few centuries in many regions of the world. Christmas is a form of Christs mass. It is derived from the Middle English Cristemasse, which is from Old English Crīstesmæsse, crīst is from Greek Khrīstos, a translation of Hebrew Māšîaḥ, Messiah, meaning anointed, and mæsse is from Latin missa, the celebration of the Eucharist. The form Christenmas was also used, but is now considered archaic and dialectal, it derives from Middle English Cristenmasse. In addition to Christmas, the holiday has been known by other names throughout its history. The Anglo-Saxons referred to the feast as midwinter, or, more rarely, Nativity, meaning birth, is from Latin nātīvitās. In Old English, Gēola referred to the corresponding to December and January. Noel entered English in the late 14th century and is from the Old French noël or naël, itself ultimately from the Latin nātālis, the canonical gospels of Luke and Matthew both describe Jesus as being born in Bethlehem in Judea, to a virgin mother. In the Gospel of Luke account, Joseph and Mary travel from Nazareth to Bethlehem for the census and it says that angels proclaimed him a savior for all people, and shepherds came to adore him. In the Matthew account, magi follow a star to Bethlehem to bring gifts to Jesus, King Herod orders the massacre of all the boys less than two years old in Bethlehem, but the family flees to Egypt and later settles in Nazareth. The Nativity stories of Matthew and Luke are prominent in the gospels, the first recorded Christmas celebration was in Rome in 336. Christmas played a role in the Arian controversy of the fourth century, the feast regained prominence after 800, when Charlemagne was crowned emperor on Christmas Day

11.
Leap second
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A leap second is a one-second adjustment that is occasionally applied to Coordinated Universal Time in order to keep its time of day close to the mean solar time, or UT1. Without such a correction, time reckoned by Earths rotation drifts away from atomic time because of irregularities in the Earths rate of rotation. Since this system of correction was implemented in 1972,27 leap seconds have been inserted, like most time standards, UTC defines a grouping of seconds into minutes, hours, days, months, and years. However, the duration of one solar day is now slightly longer than 24 hours because the rotation of the Earth has slowed down. The purpose of a second is to compensate for this drift. Specifically, a leap second is inserted between second 23,59,59 of a chosen UTC calendar date and second 00,00,00 of the following date. All leap seconds have been scheduled for either June 30 or December 31, the extra second is displayed on UTC clocks as 23,59,60. On clocks that display local time tied to UTC, the second may be inserted at the end of some other hour. A negative leap second would suppress second 23,59,59 of the last day of a chosen month, since the introduction of leap seconds, the mean solar day has outpaced UTC only for very brief periods, and has not triggered a negative leap second. Because the Earths rotation speed varies in response to climatic and geological events, UTC leap seconds are irregularly spaced, with this definition, the second was proposed in 1874 as the base unit of time in the CGS system of units. Because the tropical year was considered more fundamental than the year, in 1955. That value agreed to 1 part in 1010 with the second then in use. It was also close to 1⁄86400 of the solar day as averaged between years 1750 and 1892. However, for the past several centuries, the length of the solar day has been increasing by about 1. 4–1.7 ms per century. By 1961, the solar day was already a millisecond or two longer than 86,400 SI seconds. Thus, from 1961 to 1971, the rate of clocks was constantly slowed to remain synchronised with GMT. During that period, therefore, the seconds of broadcast services were actually longer than the SI second. By then, the UTC clock was already 10 seconds behind TAI, which had been synchronized with UT1 in 1958, but had been counting true SI seconds since then

12.
Coordinated Universal Time
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Coordinated Universal Time, abbreviated to UTC, is the primary time standard by which the world regulates clocks and time. It is within about 1 second of mean time at 0° longitude. It is one of closely related successors to Greenwich Mean Time. For most purposes, UTC is considered interchangeable with GMT, the first Coordinated Universal Time was informally adopted on 1 January 1960. This change also adopted leap seconds to simplify future adjustments, a number of proposals have been made to replace UTC with a new system that would eliminate leap seconds, but no consensus has yet been reached. Leap seconds are inserted as necessary to keep UTC within 0.9 seconds of universal time, see the Current number of leap seconds section for the number of leap seconds inserted to date. The official abbreviation for Coordinated Universal Time is UTC and this abbreviation arose from a desire by the International Telecommunication Union and the International Astronomical Union to use the same abbreviation in all languages. English speakers originally proposed CUT, while French speakers proposed TUC, the compromise that emerged was UTC, which conforms to the pattern for the abbreviations of the variants of Universal Time. Time zones around the world are expressed using positive or negative offsets from UTC, the westernmost time zone uses UTC−12, being twelve hours behind UTC, the easternmost time zone, theoretically, uses UTC+12, being twelve hours ahead of UTC. In 1995, the nation of Kiribati moved those of its atolls in the Line Islands from UTC-10 to UTC+14 so that the country would all be on the same day. UTC is used in internet and World Wide Web standards. The Network Time Protocol, designed to synchronise the clocks of computers over the internet, computer servers, online services and other entities that rely on having a universally accepted time use UTC as it is more specific than GMT. If only limited precision is needed, clients can obtain the current UTC from a number of official internet UTC servers, for sub-microsecond precision, clients can obtain the time from satellite signals. UTC is also the standard used in aviation, e. g. for flight plans. Weather forecasts and maps all use UTC to avoid confusion about time zones, the International Space Station also uses UTC as a time standard. Amateur radio operators often schedule their radio contacts in UTC, because transmissions on some frequencies can be picked up by many time zones, UTC is also used in digital tachographs used on large goods vehicles under EU and AETR rules. UTC divides time into days, hours, minutes and seconds, days are conventionally identified using the Gregorian calendar, but Julian day numbers can also be used. Each day contains 24 hours and each hour contains 60 minutes, the number of seconds in a minute is usually 60, but with an occasional leap second, it may be 61 or 59 instead

13.
Tropical year
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Because of the precession of the equinoxes, the seasonal cycle does not remain exactly synchronized with the position of the Earth in its orbit around the Sun. As a consequence, the year is about 20 minutes shorter than the time it takes Earth to complete one full orbit around the Sun as measured with respect to the fixed stars. Since antiquity, astronomers have progressively refined the definition of the tropical year, the entry for year, tropical in the Astronomical Almanac Online Glossary 2015 states, the period of time for the ecliptic longitude of the Sun to increase 360 degrees. The mean tropical year is approximately 365 days,5 hours,48 minutes,45 seconds, an equivalent, more descriptive, definition is The natural basis for computing passing tropical years is the mean longitude of the Sun reckoned from the precessionally moving equinox. Whenever the longitude reaches a multiple of 360 degrees the mean Sun crosses the vernal equinox, the mean tropical year in 2000 was 365.24219 ephemeris days, each ephemeris day lasting 86,400 SI seconds. This is 365.24217 mean solar days, the word tropical comes from the Greek tropikos meaning turn. Thus, the tropics of Cancer and Capricorn mark the north and south latitudes where the Sun can appear directly overhead. Because of this connection between the tropics and the cycle of the apparent position of the Sun, the word tropical also lent its name to the tropical year. The early Chinese, Hindus, Greeks, and others made approximate measures of the tropical year, in the 2nd century BC Hipparchus measured the time required for the Sun to travel from an equinox to the same equinox again. He reckoned the length of the year to be 1/300 of a day less than 365.25 days, Hipparchus used this method because he was better able to detect the time of the equinoxes, compared to that of the solstices. He reckoned the value as 1° per century, a value that was not improved upon until about 1000 years later, since this discovery a distinction has been made between the tropical year and the sidereal year. During the Middle Ages and Renaissance a number of progressively better tables were published that allowed computation of the positions of the Sun, Moon, an important application of these tables was the reform of the calendar. The length of the year was given as 365 solar days 5 hours 49 minutes 16 seconds. This length was used in devising the Gregorian calendar of 1582, in the 16th century Copernicus put forward a heliocentric cosmology. This was actually less accurate than the value of the Alfonsine Tables. Major advances in the 17th century were made by Johannes Kepler, in 1609 and 1619 Kepler published his three laws of planetary motion. In 1627, Kepler used the observations of Tycho Brahe and Waltherus to produce the most accurate tables up to that time and he evaluated the mean tropical year as 365 solar days,5 hours,48 minutes,45 seconds. Newtons three laws of dynamics and theory of gravity were published in his Philosophiæ Naturalis Principia Mathematica in 1687 and these effects did not begin to be understood until Newtons time

14.
Solstice
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The Solstice occurs twice each year as the Sun reaches its most northerly or southerly excursion relative to the celestial equator on the celestial sphere. The seasons of the year are directly connected to both the solstices and the equinoxes, the term solstice can also be used in a broader sense, as the day when this occurs. The day of the solstice has either the most sunlight of the year or the least sunlight of the year for any other than the equator. Alternative terms, with no ambiguity as to which hemisphere is the context, are June solstice and December solstice, at latitudes outside the tropics, the summer solstice marks the day when the sun appears highest in the sky. Within the tropics, the sun directly overhead from days to months before the solstice and again after the solstice. For an observer on the North Pole, the sun reaches the highest position in the sky once a year in June, the day this occurs is called the June solstice day. Similarly, for an observer on the South Pole, the sun reaches the highest position on December solstice day, when it is the summer solstice at one Pole, it is the winter solstice on the other. The suns westerly motion never ceases as the Earth is continually in rotation, however, the suns motion in declination comes to a stop at the moment of solstice. In that sense, solstice means sun-standing and this modern scientific word descends from a Latin scientific word in use in the late Roman republic of the 1st century BC, solstitium. Pliny uses it a number of times in his Natural History with a meaning that it has today. It contains two Latin-language morphemes, sol, sun, and -stitium, stoppage, the Romans used standing to refer to a component of the relative velocity of the Sun as it is observed in the sky. Relative velocity is the motion of an object from the point of view of an observer in a frame of reference, from a fixed position on the ground, the sun appears to orbit around the Earth. To an observer in a frame of reference, the planet Earth is seen to rotate about an axis. The Earths axis is tilted with respect to the plane of the Earths orbit, an observer on Earth therefore sees a solar path that is the result of both rotation and revolution. At maximum or minimum elevation, the relative motion of the Sun perpendicular to the horizon stops. Outside of the tropics, the maximum occurs at the summer solstice. The path of the Sun, or ecliptic, sweeps north and south between the northern and southern hemispheres, the days are longer around the summer solstice and shorter around the winter solstice. When the Suns path crosses the equator, the length of the nights at latitudes +L° and -L° are of equal length and this is known as an equinox

15.
Easter
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It is the culmination of the Passion of Jesus, preceded by Lent, a forty-day period of fasting, prayer, and penance. In Western Christianity, Eastertide, or the Easter Season, begins on Easter Sunday and lasts seven weeks, ending with the coming of the fiftieth day, Pentecost Sunday. In Eastern Christianity, the season of Pascha begins on Pascha and ends with the coming of the fortieth day, the Feast of the Ascension. The First Council of Nicaea established two rules, independence of the Jewish calendar and worldwide uniformity, which were the rules for Easter explicitly laid down by the council. No details for the computation were specified, these were worked out in practice and it has come to be the first Sunday after the ecclesiastical full moon that occurs on or soonest after 21 March, but calculations vary. Easter is linked to the Jewish Passover by much of its symbolism, in many languages, the words for Easter and Passover are identical or very similar. Easter customs vary across the Christian world, and include services, exclaiming the Paschal greeting, clipping the church. The Easter lily, a symbol of the resurrection, traditionally decorates the area of churches on this day. Additional customs that have associated with Easter and are observed by both Christians and some non-Christians include egg hunting, the Easter Bunny, and Easter parades. There are also various traditional Easter foods that vary regionally, however, it is possible that Bede was only speculating about the origin of the term since there is no firm evidence that such a goddess actually existed. In Greek and Latin, the Christian celebration was, and still is, called Πάσχα, Pascha, the word originally denoted the Jewish festival known in English as Passover, commemorating the Jewish Exodus from slavery in Egypt. In most of the non-English speaking world, the feast is known by names derived from Greek, Pascha is also a name by which Jesus himself is remembered in the Orthodox Church, especially in connection with his resurrection and with the season of its celebration. The New Testament states that the resurrection of Jesus, which Easter celebrates, is a foundation of the Christian faith, the resurrection established Jesus as the powerful Son of God and is cited as proof that God will judge the world in righteousness. For those who trust in Jesus death and resurrection, death is swallowed up in victory, any person who chooses to follow Jesus receives a new birth into a living hope through the resurrection of Jesus Christ from the dead. Through faith in the working of God those who follow Jesus are spiritually resurrected with him so that they may walk in a new way of life and receive eternal salvation. Easter is linked to the Passover and Exodus from Egypt recorded in the Old Testament through the Last Supper, sufferings and crucifixion of Jesus that preceded the resurrection. According to the New Testament, Jesus gave the Passover meal a new meaning, as in the room during the Last Supper he prepared himself. He identified the matzah and cup of wine as his soon to be sacrificed

16.
Full moon
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A full moon is the lunar phase that occurs when the Moon is completely illuminated as seen from Earth. This occurs when Earth is located directly between the Sun and the Moon and this means that the hemisphere of the Moon that is facing Earth is almost fully illuminated by the Sun and appears round. On some occasions at the time of full moon there is also a lunar eclipse so the face appears reddish due to the rayleigh scattering of blue light in Earths atmosphere. Lunar eclipses can occur only at full moon, where the Moons orbit allows it to pass through Earths shadow, Lunar eclipses do not occur every month because the Moon usually passes above or below Earths shadow. Lunar eclipses can only when the full moon occurs near the two nodes of the orbit, either the ascending or descending node. This causes eclipses to occur about every 6 months. The time interval between similar lunar phases—the synodic month—averages about 29.53 days, therefore, in those lunar calendars in which each month begins on the new moon, the full moon falls on either the 14th or 15th of the lunar month. Because calendar months have a number of days, lunar months may be either 29 or 30 days long. A full moon is thought of as an event of a full nights duration. This is somewhat misleading because the Moon seen from Earth is continuously becoming larger and/or smaller and its absolute maximum size occurs at the moment expansion has stopped. For any given location, about half of these absolute maximum full moons will be visible, as the other half occur during the day. Many almanacs list full moons not just by date, but by their time as well. Typical monthly calendars that include phases of the Moon may be offset by one day if intended for use in a different time zone, Full moons are generally a poor time to conduct astronomical observations, because the bright reflected sunlight from the Moon overwhelms the dimmer light from stars. On 12 December 2008, the moon occurred closer to the Earth than it had been at any time for the previous 15 years. On 19 March 2011, another full moon occurred, closer to the Earth than at any time for the previous ~18 years. On 14 November 2016, a full moon occurred closer to the Earth than at any time for the previous 68 years. The true time of a full moon may differ from this approximation by up to about 14.5 hours as a result of the non-circularity of the moons orbit, see New moon for an explanation of the formula and its parameters. The age and apparent size of the full moon vary in a cycle of just under 14 synodic months, Full moons are traditionally associated with temporal insomnia, insanity and various magical phenomena such as lycanthropy

17.
Divisor
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In mathematics, a divisor of an integer n, also called a factor of n, is an integer m that may be multiplied by some other integer to produce n. In this case one says also that n is a multiple of m, an integer n is divisible by another integer m if m is a divisor of n, this implies dividing n by m leaves no remainder. Under this definition, the statement m ∣0 holds for every m, as before, but with the additional constraint k ≠0. Under this definition, the statement m ∣0 does not hold for m ≠0, in the remainder of this article, which definition is applied is indicated where this is significant. Divisors can be negative as well as positive, although sometimes the term is restricted to positive divisors. For example, there are six divisors of 4, they are 1,2,4, −1, −2, and −4,1 and −1 divide every integer. Every integer is a divisor of itself, every integer is a divisor of 0. Integers divisible by 2 are called even, and numbers not divisible by 2 are called odd,1, −1, n and −n are known as the trivial divisors of n. A divisor of n that is not a divisor is known as a non-trivial divisor. A non-zero integer with at least one divisor is known as a composite number, while the units −1 and 1. There are divisibility rules which allow one to recognize certain divisors of a number from the numbers digits, the generalization can be said to be the concept of divisibility in any integral domain. 7 is a divisor of 42 because 7 ×6 =42 and it can also be said that 42 is divisible by 7,42 is a multiple of 7,7 divides 42, or 7 is a factor of 42. The non-trivial divisors of 6 are 2, −2,3, the positive divisors of 42 are 1,2,3,6,7,14,21,42. 5 ∣0, because 5 ×0 =0, if a ∣ b and b ∣ a, then a = b or a = − b. If a ∣ b and a ∣ c, then a ∣ holds, however, if a ∣ b and c ∣ b, then ∣ b does not always hold. If a ∣ b c, and gcd =1, then a ∣ c, if p is a prime number and p ∣ a b then p ∣ a or p ∣ b. A positive divisor of n which is different from n is called a proper divisor or a part of n. A number that does not evenly divide n but leaves a remainder is called an aliquant part of n, an integer n >1 whose only proper divisor is 1 is called a prime number

18.
Julian calendar
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The Julian calendar, proposed by Julius Caesar in 46 BC, was a reform of the Roman calendar. It took effect on 1 January 45 BC, by edict, the Julian calendar gains against the mean tropical year at the rate of one day in 128 years. For the Gregorian the figure is one day in 3,030 years, the difference in the average length of the year between Julian and Gregorian is 0. 002%. The Julian calendar has a year of 365 days divided into 12 months. A leap day is added to February every four years, the Julian year is, therefore, on average 365.25 days long. It was intended to approximate the tropical year, as a result, the calendar year gains about three days every four centuries compared to observed equinox times and the seasons. This discrepancy was corrected by the Gregorian reform of 1582, consequently, the Julian calendar is currently 13 days behind the Gregorian calendar. Egypt converted on 20 December 1874/1 January 1875, turkey switched on 16 February/1 March 1917. Russia changed on 1/14 February 1918, Greece made the change for civil purposes on 16 February/1 March 1923 - the national day, which was a religious holiday, was to remain on the old calendar. Most Christian denominations in the west and areas evangelised by western churches have replaced the Julian calendar with the Gregorian as the basis for their liturgical calendars. However, most branches of the Eastern Orthodox Church still use the Julian calendar for calculating the date of Easter, some Orthodox churches have adopted the Revised Julian calendar for the observance of fixed feasts, while other Orthodox churches retain the Julian calendar for all purposes. The Julian calendar is used by the Berbers of the Maghreb in the form of the Berber calendar. In the form of the Alexandrian calendar, it is the basis for the Ethiopian calendar, during the changeover between calendars and for some time afterwards, dual dating was used in documents and gave the date according to both systems. In contemporary as well as texts that describe events during the period of change. The ordinary year in the previous Roman calendar consisted of 12 months, in addition, a 27- or 28-day intercalary month, the Mensis Intercalaris, was sometimes inserted between February and March. The net effect was to add 22 or 23 days to the year, some say the mensis intercalaris always had 27 days and began on either the first or the second day after the Terminalia. According to the later writers Censorinus and Macrobius, the ideal intercalary cycle consisted of ordinary years of 355 days alternating with intercalary years, alternately 377 and 378 days long. In this system, the average Roman year would have had 366 1⁄4 days over four years, Macrobius describes a further refinement whereby, in one 8-year period within a 24-year cycle, there were only three intercalary years, each of 377 days

19.
Roman calendar
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The Roman calendar is the calendar used by the Roman kingdom and republic. The original calendar consisted of 10 months beginning in spring with March and these months ran for 38 nundinal cycles, each forming a kind of eight day week ended by religious rituals and a public market. The winter period was used to create January and February. The legendary early kings Romulus and Numa were traditionally credited with establishing this early fixed calendar, in particular, the kalends, nones, and ides seem to have derived from the first sighting of the crescent moon, the first-quarter moon, and the full moon respectively. The system ran well short of the year, and it needed constant intercalation to keep religious festivals. For superstitious reasons, such intercalation occurred within the month of February even after it was no longer considered the last month. Having won his war with Pompey, Caesar used his position as Romes chief pontiff to enact a calendar reform in 46 BC, in order to bring the calendar back to its proper place, Augustus was obliged to suspend intercalation for a few decades. The original Roman calendar is believed to have been a lunar calendar whose months began from the first signs of a new crescent moon. Because a lunar cycle is about 29½ days long, such months would have varied between 29 and 30 days, Romes 8-day week, the nundinal cycle, was shared with the Etruscans, who used it as the schedule of royal audiences. It was presumably a feature of the calendar and was credited in Roman legend variously to Romulus and Servius Tullius. The Romans themselves described their first organized year as one with ten fixed months, such a decimal division fit general Roman practice. The four 31-day months were called full and the others hollow and its 304 days made up exactly 38 nundinal cycles. Later Roman writers credited this calendar to Romulus, their legendary first king and culture hero, although this was common with other practices and traditions whose origin had been lost to them. Rüpke also finds the coincidence of the length of the supposed Romulan year with the length of the first ten months of the Julian calendar to be suspicious, other traditions existed alongside this one, however. Plutarchs Parallel Lives recounts that Romuluss calendar had been solar but adhered to the principle that the year should last for 360 days. Months were employed secondarily and haphazardly, with some counted as 20 days, the attested calendar of the Roman Republic was quite different. It followed Greek calendars in assuming a lunar cycle of 29½ days and a year of 12½ synodic months. The additional two months of the year were January and February, the month was sometimes known as Mercedonius

20.
Syzygy (astronomy)
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In astronomy, a syzygy is a straight-line configuration of three celestial bodies in a gravitational system. The word is used in reference to the Sun, Earth, and either the Moon or a planet. Solar and lunar eclipses occur at times of syzygy, as do transits, the term is often applied when the Sun and Moon are in conjunction or opposition. The word syzygy is often used to describe interesting configurations of planets in general. For example, one such case occurred on March 21,1894 around 23,00 GMT, when Mercury transited the Sun, and Mercury and Venus both simultaneously transited the Sun as seen from Saturn. It is also used to describe situations when all the planets are on the side of the Sun although they are not necessarily in a straight line. On June 3,2014, the Curiosity rover on Mars observed the planet Mercury transiting the Sun, syzygy sometimes results in an occultation, transit, or eclipse. An occultation occurs when a larger body passes in front of an apparently smaller one. A transit occurs when a smaller body passes in front of a larger one, in the combined case where the smaller body regularly transits the larger, an occultation is also termed a secondary eclipse. An eclipse occurs when a body totally or partially disappears from view, either by an occultation, as with an eclipse, or by passing into the shadow of another body. Transits and occultations of the Sun by Earths Moon are called solar eclipses regardless of whether the Sun is completely or partially covered, the term eclipse is also used more generally for bodies passing in front of one another. For example, a NASA Astronomy Picture of the Day refers to the Moon eclipsing and occulting Saturn interchangeably, syzygy causes the bimonthly phenomena of spring and neap tides. At the new and full moon, the Sun and Moon are in syzygy and their tidal forces act to reinforce each other, and the ocean both rises higher and falls lower than the average. Conversely, at the first and third quarter, the Sun and Moon are at angles, their tidal forces counteract each other. Tidal variation can also be measured in the earths crust, and this may affect the frequency of earthquakes

21.
Lunar phase
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The lunar phase or phase of the moon is the shape of the illuminated portion of the Moon as seen by an observer on Earth. The lunar phases change cyclically as the Moon orbits the Earth, according to the positions of the Moon. The Moons rotation is locked by the Earths gravity, therefore the same lunar surface always faces Earth. This face is variously sunlit depending on the position of the Moon in its orbit, therefore, the portion of this hemisphere that is visible to an observer on Earth can vary from about 100% to 0%. The lunar terminator is the boundary between the illuminated and darkened hemispheres, each of the four intermediate lunar phases is roughly seven days but this varies slightly due to the elliptical shape of the Moons orbit. Aside from some craters near the lunar poles such as Shoemaker, all parts of the Moon see around 14.77 days of sunlight, in Western culture, the four principal lunar phases are new moon, first quarter, full moon, and third quarter. These are the instants when the Moons apparent geocentric celestial longitude minus the Suns apparent geocentric longitude is 0°, 90°, 180° and 270°. Each of these phases is instantaneous, lasting theoretically zero time, during the intervals between principal phases, the Moon appears either crescent-shaped or gibbous. These shapes, and the periods of time when the Moon shows them, are called the intermediate phases. They last, on average, one-quarter of a month, roughly 7.38 days, but their durations vary slightly because the Moons orbit is slightly elliptical. The descriptor waxing is used for a phase when the Moons apparent size is increasing, from new moon toward full moon. As the moon waxes, the lunar phases progress through new moon, crescent moon, first-quarter moon, gibbous moon, the moon is then said to wane as it passes through the gibbous moon, third-quarter moon, crescent moon and back to new moon. The terms old moon and new moon are not interchangeable, the old moon is a waning sliver until the moment it aligns with the sun and begins to wax, at which point it becomes new again. Half moon is used to mean the first- and third-quarter moons, while the term quarter refers to the extent of the moons cycle around the Earth. When a crescent Moon occurs, the phenomenon of earthshine may be apparent, in the Northern Hemisphere, if the left side of the Moon is dark then the light part is growing, and the Moon is referred to as waxing. If the right side of the Moon is dark then the part is shrinking. Assuming that the viewer is in the hemisphere, the right portion of the Moon is the part that is always growing. Nearer the Equator the Moon with its terminator will appear apparently horizontal during the morning and evening, the crescent Moon can open upward or downward, with the horns of the crescent pointing up or down, respectively

22.
Christian Ludwig Ideler
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Christian Ludwig Ideler was a German chronologist and astronomer. He was born in Gross-Brese near Perleberg and his earliest work was the editing in 1794 of an astronomical almanac for the Prussian government. He taught mathematics and mechanics in the school of woods and forests, in 1821, he became professor at the University of Berlin, and in 1829 became a foreign member of the Institute of France. From 1816 to 1822 he was tutor to the young princes William Frederick and he died in Berlin on 10 August 1846. He devoted his life chiefly to the examination of ancient systems of chronology and he wrote also Historische Untersuchungen über die astronomischen Beobachtungen der Alten, Untersuchungen über den Ursprung und die Bedeutung der Sternnamen and Über den Ursprung des Thierkreises. With Nolte he published handbooks on English and French language and literature and his son, Julius Ludwig Ideler, wrote Meteorologia veterum Graecorum et Romanorum. This article incorporates text from a now in the public domain, Chisholm, Hugh, ed. Ideler. This source reports Ideler becoming a member of the French Institute 18 years after becoming a professor in Berlin, ripley, George, Dana, Charles A. eds. Thurston, H. T. Colby, F. M. eds

23.
Decemvirs
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The decemviri or decemvirs were any of several 10-man commissions established by the Roman Republic. Other decemviri include the Decemviri Adjudging Litigation, the Decemviri Making Sacrifices, the setting up of the Decemviri Legibus Scribundis Consulari Imperio occurred within the context of the two hundred-year Conflict of the Orders between the patrician order and the plebeian order. The form of labour exploitation during this period was the nexum. The debtor pledged his services as collateral for debt. Defaulting debtors were liable to have their labour bonded for life and this also led to an increase in the problem of the abuse of defaulting debtors. Because of the absence of clearly defined laws and judicial procedures and this led to the First Plebeian Secession, which was the start of the Conflict of the Orders. The plebeians demanded the state to protect farmers from the abuse of defaulting debtors by the creditors. When this was not forthcoming, they resorted to boycotting the levy, at that time the Roman army was a part-time militia of peasant farmers who were drafted each year for the military campaigning season and then went back to their farms. Refusing the call-up gave plebeians significant political leverage, when their demands were not met, on their return from a defensive military campaign the soldiers refused to obey orders and seceded to Mons Sacer, outside Rome. They threatened to stay there until their demands were met, there were negotiations and the secession ended. However, the demands were not fully met. Rather, they obtained the recognition of the institutions which they had created during the rebellion, the Plebeian Council, the latter acted as the defenders of the plebeians from abuse by consuls or officials through the provocatio, the power to veto the actions of the consuls and officials. They used it for actions they judged inequitable or abusive to any plebeian and they also convened and presided over the Plebeian Council and presented bills for its vote. An element of this conflict was about whether the resolutions of this council should be binding on all Roman citizens, including the patricians, the plebeian institutions were parallel and separate from that of the Roman state. Livy said wo states had created out of one, each faction had its own magistrates. The main role of the institutions in the early days of the conflict of the orders was self-defence. The next step in the conflict was the Lex Terentilia proposed by Gaius Terentilius Harsa and it provided for a five-man commission to set out the norms through which the power of the consuls would be defined. With the overthrow of the monarchy and the establishment of the republic, the powers of the king were transferred to the consuls, as such, consular powers were undefined and therefore without limits

24.
Ancient Rome
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In its many centuries of existence, the Roman state evolved from a monarchy to a classical republic and then to an increasingly autocratic empire. Through conquest and assimilation, it came to dominate the Mediterranean region and then Western Europe, Asia Minor, North Africa and it is often grouped into classical antiquity together with ancient Greece, and their similar cultures and societies are known as the Greco-Roman world. Ancient Roman civilisation has contributed to modern government, law, politics, engineering, art, literature, architecture, technology, warfare, religion, language and society. Rome professionalised and expanded its military and created a system of government called res publica, the inspiration for modern republics such as the United States and France. By the end of the Republic, Rome had conquered the lands around the Mediterranean and beyond, its domain extended from the Atlantic to Arabia, the Roman Empire emerged with the end of the Republic and the dictatorship of Augustus Caesar. 721 years of Roman-Persian Wars started in 92 BC with their first war against Parthia and it would become the longest conflict in human history, and have major lasting effects and consequences for both empires. Under Trajan, the Empire reached its territorial peak, Republican mores and traditions started to decline during the imperial period, with civil wars becoming a prelude common to the rise of a new emperor. Splinter states, such as the Palmyrene Empire, would divide the Empire during the crisis of the 3rd century. Plagued by internal instability and attacked by various migrating peoples, the part of the empire broke up into independent kingdoms in the 5th century. This splintering is a landmark historians use to divide the ancient period of history from the pre-medieval Dark Ages of Europe. King Numitor was deposed from his throne by his brother, Amulius, while Numitors daughter, Rhea Silvia, because Rhea Silvia was raped and impregnated by Mars, the Roman god of war, the twins were considered half-divine. The new king, Amulius, feared Romulus and Remus would take back the throne, a she-wolf saved and raised them, and when they were old enough, they returned the throne of Alba Longa to Numitor. Romulus became the source of the citys name, in order to attract people to the city, Rome became a sanctuary for the indigent, exiled, and unwanted. This caused a problem for Rome, which had a large workforce but was bereft of women, Romulus traveled to the neighboring towns and tribes and attempted to secure marriage rights, but as Rome was so full of undesirables they all refused. Legend says that the Latins invited the Sabines to a festival and stole their unmarried maidens, leading to the integration of the Latins, after a long time in rough seas, they landed at the banks of the Tiber River. Not long after they landed, the men wanted to take to the sea again, one woman, named Roma, suggested that the women burn the ships out at sea to prevent them from leaving. At first, the men were angry with Roma, but they realized that they were in the ideal place to settle. They named the settlement after the woman who torched their ships, the Roman poet Virgil recounted this legend in his classical epic poem the Aeneid

25.
Terminus (god)
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In Roman religion, Terminus was the god who protected boundary markers, his name was the Latin word for such a marker. Sacrifices were performed to each boundary stone, and landowners celebrated a festival called the Terminalia in Terminus honor each year on February 23. Ancient writers believed that the worship of Terminus had been introduced to Rome during the reign of the first king Romulus or his successor Numa. The name of the god Terminus was the Latin word for a boundary stone, on February 23 annually, a festival called the Terminalia was celebrated in Terminus honor, involving practices which can be regarded as a reflection or yearly renewal of this foundational ritual. Neighboring families would garland their respective sides of the marker and make offerings to Terminus at an altar—Ovid identifies these, again, as crops, honeycombs, the marker itself would be drenched in the blood of a sacrificed lamb or pig. There followed a communal feast and hymns in praise of Terminus and these rites were practised by private landowners, but there were also related public ceremonies. Also, a stone or altar of Terminus was located in the Temple of Jupiter Optimus Maximus on Romes Capitoline Hill, because of a belief that this stone had to be exposed to the sky, there was a small hole in the ceiling directly above it. There is some evidence that Terminus associations could extend from property boundaries to limits more generally, diocletians decision in 303 AD to initiate his persecution of Christians on February 23 has been seen as an attempt at enlisting Terminus to put a limit to the progress of Christianity. Those authors who gave the credit to Numa explained his motivation as the prevention of violent disputes over property, plutarch further states that, in keeping with Terminuss character as a guarantor of peace, his earliest worship did not involve blood sacrifices. The stone in the Capitoline Temple was believed to have been among the altars located on the Capitoline Hill before the Temple was built under Tarquinius Priscus or Tarquinius Superbus. The stone was therefore included within the Capitoline Temple, and its immovability was regarded as an omen for the permanence of the citys boundaries. Terminus, with his lack of mythology and his association with a physical object. This view of Terminus retains some recent adherents, but other scholars have argued from Indo-European parallels that the gods of Roman religion must have preceded the citys foundation. Georges Dumézil regarded Jupiter, Juventas and Terminus as the Roman form of a triad, comparing the Roman deities respectively to the Vedic Mitra, Aryaman. In this view the sovereign god was associated with two deities, one concerned with the entry of men into society and the other with the fair division of their goods. Terminus, I segni di confine nella religione romana, woodard, Roger D. Indo-European Sacred Space. Reviewed by Marco V. García-Quintela, Bryn Mawr Classical Review 2007.02.36, the dictionary definition of Terminus at Wiktionary Britannica Online Encyclopædia Roman Mythology Index, Terminus Myths about the Roman God Terminus

26.
Julius Caesar
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Gaius Julius Caesar, known as Julius Caesar, was a Roman politician, general, and notable author of Latin prose. He played a role in the events that led to the demise of the Roman Republic. In 60 BC, Caesar, Crassus, and Pompey formed an alliance that dominated Roman politics for several years. Their attempts to power as Populares were opposed by the Optimates within the Roman Senate. Caesars victories in the Gallic Wars, completed by 51 BC, extended Romes territory to the English Channel, Caesar became the first Roman general to cross both the Channel and the Rhine, when he built a bridge across the Rhine and crossed the Channel to invade Britain. These achievements granted him unmatched military power and threatened to eclipse the standing of Pompey, with the Gallic Wars concluded, the Senate ordered Caesar to step down from his military command and return to Rome. Caesar refused the order, and instead marked his defiance in 49 BC by crossing the Rubicon with the 13th Legion, leaving his province, Civil war resulted, and Caesars victory in the war put him in an unrivalled position of power and influence. After assuming control of government, Caesar began a programme of social and governmental reforms and he centralised the bureaucracy of the Republic and was eventually proclaimed dictator in perpetuity, giving him additional authority. But the underlying political conflicts had not been resolved, and on the Ides of March 44 BC, a new series of civil wars broke out, and the constitutional government of the Republic was never fully restored. Caesars adopted heir Octavian, later known as Augustus, rose to power after defeating his opponents in the civil war. Octavian set about solidifying his power, and the era of the Roman Empire began, much of Caesars life is known from his own accounts of his military campaigns, and from other contemporary sources, mainly the letters and speeches of Cicero and the historical writings of Sallust. The later biographies of Caesar by Suetonius and Plutarch are also major sources, Caesar is considered by many historians to be one of the greatest military commanders in history. Caesar was born into a family, the gens Julia. The cognomen Caesar originated, according to Pliny the Elder, with an ancestor who was born by Caesarean section. The Historia Augusta suggests three alternative explanations, that the first Caesar had a head of hair, that he had bright grey eyes. Caesar issued coins featuring images of elephants, suggesting that he favored this interpretation of his name, despite their ancient pedigree, the Julii Caesares were not especially politically influential, although they had enjoyed some revival of their political fortunes in the early 1st century BC. Caesars father, also called Gaius Julius Caesar, governed the province of Asia and his mother, Aurelia Cotta, came from an influential family. Little is recorded of Caesars childhood, in 85 BC, Caesars father died suddenly, so Caesar was the head of the family at 16

27.
Macrobius
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Only in later manuscripts were his names reversed as Ambrosius Theodosius Macrobius, which James Willis then adopted for his edition of the Commentary. Little is known for certain about Macrobius, but there are many theories and he states at the beginning of his Saturnalia that he was born under a foreign sky, and both of his major works are dedicated to his son, Eustachius. His major works have led experts to assume that he was a pagan, which foreign sky Macrobius was born under has been the subject of much speculation. Terrot Glover considers Macrobius either an ethnic Greek, or born in one of the Greek-speaking parts of the Roman Empire, such as Egypt, J. E. Sandys went further and argued that Macrobius was born in one of the Greek provinces. Scholars have attempted to identify him with a Macrobius who is mentioned in the Codex Theodosianus as a prefect of Spain. The Codex Theodosianus also records a praepositus named Macrobius in 422, a number of older authorities go so far as to identify Macrobius the author with the first, and date his floruit to 399–410. Further, Cameron points out that during his lifetime Macrobius was referred to as Theodosius and it is significant that the only surviving law addressed to this Theodosius sanctions a privilege for Africa Proconsularis on the basis of information received concerning Byzacena, Cameron notes. Macrobiuss most influential one of the most widely cited books of the Middle Ages—was a commentary in two books on the Dream of Scipio narrated by Cicero at the end of his Republic. In astronomy, this work is noted for giving the diameter of the Sun as twice the diameter of the Earth. Of a third work On the Differences and Similarities of the Greek and Latin Verb, we possess an abstract by a certain Johannes. See editions by Ludwig von Jan, Franz Eyssenhardt, James Willis, the grammatical treatise will be found in Jans edition and Heinrich Keils Grammatici latini, see also Georg Friedrich Schömann, Commentatio macrobiana. Macrobiuss Saturnalia consists of an account of the held at the house of Vettius Agorius Praetextatus during the holiday of the Saturnalia. It contains a variety of curious historical, mythological, critical, antiquarian. The work takes the form of a series of dialogues among learned men at a fictional banquet. The latter part of the book is taken up with a dissertation upon luxury and the sumptuary laws intended to check it. The seventh book consists largely of the discussion of various physiological questions, the primary value of the work lies in the facts and opinions quoted from earlier writers. Cambridge, MA/ London, Harvard University Press,2011, percival Vaughan Davies, Macrobius, The Saturnalia. New York, Columbia University Press,1969, william Harris Stahl, Macrobius, Commentary on the Dream of Scipio

28.
Bede
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He is well known as an author and scholar, and his most famous work, Ecclesiastical History of the English People gained him the title The Father of English History. Bedes monastery had access to a library which included works by Eusebius, Orosius. Almost everything that is known of Bedes life is contained in the last chapter of his Ecclesiastical History of the English People, a history of the church in England. It was completed in about 731, and Bede implies that he was then in his fifty-ninth year, a minor source of information is the letter by his disciple Cuthbert which relates Bedes death. Bede, in the Historia, gives his birthplace as on the lands of this monastery, Bede says nothing of his origins, but his connections with men of noble ancestry suggest that his own family was well-to-do. Bedes first abbot was Benedict Biscop, and the names Biscop, Bedes name reflects West Saxon Bīeda. It is an Anglo-Saxon short name formed on the root of bēodan to bid, the name also occurs in the Anglo-Saxon Chronicle, s. a. 501, as Bieda, one of the sons of the Saxon founder of Portsmouth, the Liber Vitae of Durham Cathedral names two priests with this name, one of whom is presumably Bede himself. Some manuscripts of the Life of Cuthbert, one of Bedes works, mention that Cuthberts own priest was named Bede, at the age of seven, Bede was sent to the monastery of Monkwearmouth by his family to be educated by Benedict Biscop and later by Ceolfrith. Bede does not say whether it was intended at that point that he would be a monk. Monkwearmouths sister monastery at Jarrow was founded by Ceolfrith in 682, in 686, plague broke out at Jarrow. The two managed to do the service of the liturgy until others could be trained. The young boy was almost certainly Bede, who would have been about 14, when Bede was about 17 years old, Adomnán, the abbot of Iona Abbey, visited Monkwearmouth and Jarrow. Bede would probably have met the abbot during this visit, in about 692, in Bedes nineteenth year, Bede was ordained a deacon by his diocesan bishop, John, who was bishop of Hexham. There might have been minor orders ranking below a deacon, in Bedes thirtieth year, he became a priest, with the ordination again performed by Bishop John. In about 701 Bede wrote his first works, the De Arte Metrica and De Schematibus et Tropis and he continued to write for the rest of his life, eventually completing over 60 books, most of which have survived. Not all his output can be dated, and Bede may have worked on some texts over a period of many years. His last-surviving work is a letter to Ecgbert of York, a former student, Bede may also have worked on one of the Latin bibles that were copied at Jarrow, one of which is now held by the Laurentian Library in Florence

29.
Computus
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Computus is a calculation that determines the calendar date of Easter. The name has been used for this procedure since the early Middle Ages, for most of their history Christians have calculated Easter independently of the Jewish calendar. In principle, Easter falls on the Sunday following the moon that follows the northern spring equinox. However, the equinox and the full moon are not determined by astronomical observation. The vernal equinox is fixed to fall on 21 March, the full moon is an ecclesiastical full moon determined by reference to a lunar calendar, which again varied in different areas. The last limit arises from the fact that the crucifixion was considered to have happened on the 14th, the synodic month had already been measured to a high degree of accuracy. The schematic model that eventually was accepted is the Metonic cycle, in 1583, the Catholic Church began using 21 March under the Gregorian calendar to calculate the date of Easter, while the Eastern Churches have continued to use 21 March under the Julian calendar. The Catholic and Protestant denominations thus use a full moon that occurs four. The earliest and latest dates for Easter are 22 March and 25 April, in the Gregorian calendar those dates are as commonly understood. Easter is the most important Christian feast, and the date of its celebration has been the subject of controversy as early as the meeting of Anicetus. The rest of the Christian world at time, according to Eusebius, held to the view which still prevails. Eusebius does not say how the Sunday was decided, by the end of the 3rd century some Christians had become dissatisfied with what they perceived as the disorderly state of the Jewish calendar. The chief complaint was that the Jewish practice sometimes set the 14th of Nisan before the spring equinox, and it was explicitly stated by Peter, bishop of Alexandria that the men of the present day now celebrate before the equinox. through negligence and error. Another objection to using the Jewish computation may have been that the Jewish calendar was not unified, Jews in one city might have a method for reckoning the Week of Unleavened Bread different from that used by the Jews of another city. Because of these perceived defects in the practice, Christian computists began experimenting with systems for determining Easter that would be free of these defects. At the First Council of Nicaea in 325, it was agreed that the Christians should observe a common date, because of the divergence of tables mentioned above it was usual to negotiate a common date when discrepancies arose. It took several centuries before a common method was accepted throughout Christendom, the process of working out the details generated still further controversies. The method from Alexandria became authoritative, in its developed form it was based on the epacts of a reckoned moon according to the 19-year Metonic cycle

30.
Roman Missal
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The Roman Missal is the liturgical book that contains the texts and rubrics for the celebration of the Mass in the Roman Rite of the Catholic Church. Before the high Middle Ages, several books were used at Mass, a Sacramentary with the prayers, one or more books for the Scriptural readings, and one or more books for the antiphons and other chants. Gradually, manuscripts came into being that incorporated parts of more than one of these books, such a book was referred to as a Missale Plenum. In 1223 Saint Francis of Assisi instructed his friars to adopt the form that was in use at the Papal Court and they adapted this missal further to the needs of their largely itinerant apostolate. Its use spread throughout Europe, especially after the invention of the printing press, printing also favoured the spread of other liturgical texts of less certain orthodoxy. The Council of Trent recognized that an end must be put to the resulting confusion, some corrections to Pope Pius Vs text proved necessary, and Pope Clement VIII replaced it with a new typical edition of the Roman Missal on 7 July 1604. A further revised edition was promulgated by Pope Urban VIII on 2 September 1634. Beginning in the seventeenth century, France and neighbouring areas saw a flurry of independent missals published by bishops influenced by Jansenism and Gallicanism. This ended when Bishop Pierre-Louis Parisis of Langres and Abbot Guéranger initiated in the century a campaign to return to the Roman Missal. Pope Leo XIII then took the opportunity to issue in 1884 a new edition that took account of all the changes introduced since the time of Pope Urban VIII. Pope Pius X also undertook a revision of the Roman Missal, in the part of the Missal thus thoroughly revised, he anticipated some of the changes affecting all days of the year after the Second Vatican Council. These novelties included the first official introduction of the language into the liturgy for renewal of baptismal promises within the Easter Vigil celebration. The Pope also removed from the Vigil of Pentecost the series of six Old Testament readings, with their accompanying Tracts and Collects, the changes this made in the General Roman Calendar are indicated in General Roman Calendar of Pope Pius XII. After duly weighing the answers of the bishops, he judged that it was time to attack the problem of a general and systematic revision of the rubrics of the breviary and this question he referred to the special committee of experts appointed to study the general liturgical reform. His successor, Pope John XXIII, issued a new edition of the Roman Missal in 1962. This incorporated the revised Code of Rubrics which Pope Pius XIIs commission had prepared, other notable revisions were the omission of the adjective perfidis in the Good Friday Prayer for the Jews and the insertion of the name of Saint Joseph into the Canon of the Mass. They were reflected in the provisional vernacular translations produced in various countries when the language of the people began to be used in addition to Latin, references sometimes met in an English-language context to the 1965 Missal concern these temporary vernacular productions, not the Roman Missal itself. Even countries that had the language used different translations and varied in the amount of vernacular admitted

31.
Saint Matthias
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In the days following, Peter proposed that the assembled disciples, who numbered about one hundred and twenty, nominate two men to replace Judas. They chose Joseph called Barsabas and Matthias, then they cast lots, and the lot fell to Matthias, so he was numbered with the eleven apostles. Matthias was present with the apostles at Pentecost. No further information about Matthias is to be found in the canonical New Testament, the tradition of the Greeks says that St. Matthias planted the faith about Cappadocia and on the coasts of the Caspian Sea, residing chiefly near the port Issus. According to Nicephorus, Matthias first preached the Gospel in Judaea, an extant Coptic Acts of Andrew and Matthias, places his activity similarly in the city of the cannibals in Aethiopia. A marker placed in the ruins of the Roman fortress at Gonio in the modern Georgian region of Adjara claims that Matthias is buried at that site and he died at Sebastopolis, and was buried there, near the Temple of the Sun. Alternatively, another tradition maintains that Matthias was stoned at Jerusalem by the Jews, according to Hippolytus of Rome, Matthias died of old age in Jerusalem. Clement of Alexandria observed, Not that they became apostles through being chosen for some distinguished peculiarity of nature, but they were capable of becoming apostles on being chosen by Him who foresees even ultimate issues. Matthias, accordingly, who was not chosen along with them, surviving fragments of the lost Gospels of Matthias attribute it to Matthias, but Early Church Fathers attributed it to heretical writings in the 2nd century. The feast of Saint Matthias was included in the Roman Calendar in the 11th century, the Eastern Rites of the Eastern Orthodox Church celebrates his feast on August 9. Yet the Western Rite Parishes of the Orthodox Church continues the old Roman Rite of February 24, the Church of Englands Book of Common Prayer liturgy, as well as other older common prayer books in the Anglican Communion, celebrates Matthias on February 24. According to the newer Common Worship liturgy, he is celebrated on May 14 with a Festival, although he may be celebrated on February 24, if desired. In the Episcopal Church as well as some in the Lutheran Church, including the Lutheran Church–Missouri Synod, in Evangelical Lutheran Worship, used by the Evangelical Lutheran Church in America as well as the Evangelical Lutheran Church in Canada, the feast date for Matthias is on May 14. It is claimed that St Matthias the Apostles remains are interred in the Abbey of St. Matthias, Trier, Germany, brought there through Empress Helena of Constantinople, according to Greek sources, the remains of the apostle are buried in the castle of Gonio-Apsaros, Georgia. Attribution This article incorporates text from a now in the public domain, Herbermann, Charles

32.
Vigil
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A vigil, from the Latin vigilia meaning wakefulness, is a period of purposeful sleeplessness, an occasion for devotional watching, or an observance. The Italian word vigilia has become generalized in this sense and means eve, a vigil may be held on the eve of a major religious festival, observed by remaining awake—watchful—as a devotional exercise or ritual observance on the eve of a holy day. Such liturgical vigils usually consist of psalms, prayers and hymns, possibly a sermon or readings from the Holy Fathers, the term morning means that the observance begins on the evening before. Most likely the best known vigil is the Easter Vigil held at night between Holy Saturday and Easter Sunday, the Midnight Mass held on Christmas Eve is a remnant of this practice. Christmas Eve is a time of reflection for Christians all over the world, in the Eastern Orthodox Church an All-Night Vigil is held on the eves of Sundays and all Major Feast Days during the liturgical year. Vigils are also observed on Holy Days in the Anglican, Lutheran. When a Jewish person dies, a watch is kept over the body and Tehillim are recited constantly, in Christianity, especially the Eastern Orthodox and Roman Catholic traditions, a vigil is often held when someone is gravely ill or mourning. Prayers are said and votives are often made, Vigils extend from eventual death to burial, ritualistically to pray for a loved one, but more so their body is never left alone. All-night vigil Candlelight vigil Christian burial Pannikhida Vigils Wake

33.
Pope Alexander III
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Pope Alexander III, born Roland of Siena, was Pope from 7 September 1159 to his death in 1181. He also laid the stone for the Notre-Dame de Paris. Pope Alexander III was born in Siena, from 14th century he is referred to as a member of the aristocratic family of Bandinelli, although this has not been proven. Noonan and Rudolf Weigand have shown this to be another Rolandus and he probably studied at Bologna, where Robert of Torigni notes that he taught theology. In October 1150, Pope Eugene III created him Cardinal-Deacon of Santi Cosma e Damiano, later he became Cardinal-Priest of St Mark. In 1153, he became chancellor and was the leader of the cardinals opposed to German Emperor Frederick I Barbarossa. He negotiated the Treaty of Benevento, which restored peaceful relations between Rome and the Kingdom of Sicily, on 7 September 1159, he was chosen the successor of Pope Adrian IV. A minority of the cardinals, however, elected the cardinal priest Octavian and this meant that Alexanders legitimacy was gaining strength, as soon proved by the fact that other monarchs, such as the king of France and King Henry II of England, recognized his authority. Because of imperial strength in Italy, Alexander was forced to reside outside of Rome for a part of his pontificate. The first period he spent in France, the latter chiefly in Gaeta, Benevento, Anagni, Alexander III was the first pope known to have paid direct attention to missionary activities east of the Baltic Sea. The latter appointed a Benedictine monk Fulco as a bishop in Estonia, in 1171, Alexander became the first pope to address the situation of the Church in Finland, with Finns allegedly harassing priests and only relying on God in time of war. Besides checkmating Barbarossa, Alexander humbled King Henry II of England for the murder of Thomas Becket in 1170, to whom he was unusually close and this was the second English saint canonized by Alexander, the first being Edward the Confessor in 1161. Nonetheless, he confirmed the position of Henry as Lord of Ireland in 1172, even as a fugitive, Alexander enjoyed the favour and protection of Louis VII of France. In March 1179, Alexander III held the Third Council of the Lateran, one of the most important mediaeval church councils, the rule was altered slightly in 1996, but was restored in 2007. This synod marked the summit of Alexander IIIs power, by the judicious use of money, however, Alexander III got him into his power, so that he was deposed in January 1180. In 1181, Alexander III excommunicated King William I of Scotland and he died at Civita Castellana on 30 August 1181. Herbermann, Charles, ed. Pope Alexander III and this article incorporates text from a publication now in the public domain, Chisholm, Hugh, ed. Alexander. Myriam Soria Audebert, Pontifical Propaganda during the Schisms, Alexander III to the reconquest of Church Unity, in Convaincre et persuader, poitiers, Université de Poitiers-centre détudes supérieures de civilisation médiévale,2007

34.
Bengali calendars
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The Bengali Calendar or Bangla Calendar is a solar calendar used in the region of Bengal. A revised version of the calendar is the national and official calendar in Bangladesh, the New Year in the Bengali calendar is known as Pôhela Bôishakh. The Bengali Era or Anno Bengal, the Bengali year is 594 less than the AD or CE year in the Gregorian calendar if it is before Pôhela Bôishakh, the revised version of the Bengali calendar was officially adopted in Bangladesh in 1987. However, it is not followed in India where the traditional version continues to be followed due to occurrence of Hindu festivals based on a particular sidereal solar day. The Bengali calendar is a solar calendar, the calendar was developed by Alauddin Husain Shah, a Hussain Shahi sultan of Bengal by combining the lunar Islamic calendar with the solar calendar, prevalent in Bengal. All theories agree that the Mughal Emperor, Akbar was instrumental in promulgating the Bengali calendar, Akbar modified, developed and re introduced the Bengali Calendar in order to make tax collection easier in Bengal. The calendar was called as Tarikh-e-Elahi. Sources credit the idea to Alauddin Husain Shah, akbars royal astronomer Fathullah Shirazi developed the Bengali calendar, by synthesizing the Lunar Islamic and Solar calendars. The calendar started with the Islamic calendar value, but the Sanskrit month names were used from the earlier version, the distinctive characteristic of the Bengali year was that rather than being a lunar calendar, it was based on a union of the solar and lunar year. This was essentially a great promotion as the solar and lunar years were formulated in very diverse systems, primarily this calendar was named as Fasli Sôn and then Bônggabdô. The Bengali Year was launched on 1584 AD or 992 AH and this was the day that Akbar defeated Hemu in the clash of Panipat to ascend the throne. The month of Muharram in the year 963 AH was equal to the month of Boishakh in the Bengali calendar, in the Tarikh-e-Elahi version of the calendar, each day of the month had a separate name, and the months had different names from what they have now. The Bengali calendar consists of 6 seasons, known as Rreetu ঋতু or Kal কাল, hence after some centuries the months will shift far away from the actual seasons. But the new revised version of the Bengali calendar used in Bangladesh will continue to maintain the seasons on time as mentioned above. The Bengali Calendar incorporates the seven-day week as used by other calendars. The names of the days of the week in the Bengali Calendar are based on the Navagraha, the day begins and ends at sunrise in the Bengali calendar, unlike in the Gregorian calendar, where the day starts at midnight. Pôhela Bôishakh in West Bengal and other states of India with Bengali diaspora, is celebrated on 14/15 April of the Gregorian calendar, however, according to the revised version of the calendar, now followed in Bangladesh, Pôhela Bôishakh always falls on 14 April. It is not clear, from what ground they start counting of 1st Bengali calendar year from the 593AD, the length of a year is counted as 365 days, as in the Gregorian calendar

35.
Indian national calendar
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The Indian national calendar, sometimes called the Saka calendar, is the official civil calendar in use in India along with the Vikram Samvat calendar. It is used, alongside the Gregorian calendar, by The Gazette of India, in broadcasts by All India Radio and in calendars. The Saka calendar is used in Java and Bali among Indonesian Hindus. Nyepi, the Day of Silence, is a celebration of the Saka new year in Bali, nepals Nepal Sambat evolved from the Saka calendar. The term may also refer to the Hindu calendar, the Saka era is also commonly used by other calendars. The calendar months follow the signs of the tropical zodiac rather than the sidereal zodiac normally used with Hindu calendar, in leap years, Chaitra has 31 days and starts on March 21 instead. The months in the first half of the year all have 31 days, the names of the months are derived from older, Hindu lunisolar calendars, so variations in spelling exist, and there is a possible source of confusion as to what calendar a date belongs to. Years are counted in the Saka Era, which starts its year 0 in the year 78 of the Common Era. To determine leap years, add 78 to the Saka year - if the result is a year in the Gregorian calendar. Its structure is like the Persian calendar, despite this effort, local variations based on older sources such as the Surya Siddhanta may still exist. Senior Indian Astrophysicist Meghnad Saha was the head of the Calendar Reform Committee under the aegis of the Council of Scientific, other members of the Committee were, A. C. Banerjee, K. K. Daftari, J. S. Karandikar, Gorakh Prasad, R. V. Vaidya and it was Saha’s effort, which led to the formation of the Committee. The task before the Committee was to prepare an accurate calendar based on scientific study, the Committee had to undertake a detailed study of different calendars prevalent in different parts of the country. The task was complicated by the fact that religion and local sentiments were integral to those calendars. Indias first prime minister, Jawaharlal Nehru, in his preface to the Report of the Committee, published in 1955, wrote, “They represent past political divisions in the country…. ”Usage started officially at Chaitra 1,1879, Saka Era, or March 22,1957, Dionysian Era. However, government officials seem to ignore the New Years Day of this calendar in favour of the religious calendar. Mapping Time, The Calendar and its History by E. G, Calendars and their History Indian Calendars Positional astronomy in India Indian National Calendar abstract

36.
Thai solar calendar
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The Thai solar calendar, was adopted by King Chulalongkorn in AD1888 as the Siamese version of the Gregorian calendar, replacing the Thai lunar calendar as the legal calendar in Thailand. Years are now counted in the Buddhist Era, พุทธศักราช, พ. ศ, rtgs, Phutthasakkarat) which is 543 years ahead of the Christian/Common Era. The Siamese generally used two calendars, a sacred and a popular, in Thailand the sacred, or Buddhist Era, is reckoned to have an epochal year 0 from 11 March 543 BC, believed to be the date of the death of Gautama Buddha. King Vajiravudh changed year counting to this Buddhist Era and moved the start of the back to 1 April in 2455 BE. As there is no longer any reference to a vulgar or popular era, as previously noted, Rama VI moved the start of the year back to 1 April in 2455 BE, AD1912. On 6 September 1940, Prime Minister Phibunsongkhram decreed 1 January 1941 as the start of the year 2484 BE, to convert dates from 1 January to 31 March prior to that year, the number to add or subtract is 542, otherwise, it is 543. Example, Today, both the Common Era New Years Day and the traditional Thai New Year celebrations are public holidays in Thailand, names of the months derive from Hindu astrology names for the signs of the zodiac. Thirty-day-month names end in -ayon, from Sanskrit root āyana, the arrival of, februarys name ends in -phan, from Sanskrit bandha, fettered or bound. The day added to February in a leap year is Athikasuratin. Buddhist calendar Public holidays in Thailand Thai 6-hour clock Thai lunar calendar Time in Thailand Eade, the Calendrical Systems of Mainland South-East Asia. Handbuch der Orientalistik, Dritte Abteilung, Südostasien 9, leiden and New York, E. J. Brill. นายเปลื้อง ณ นคร ผู้รวบรวม ปทานุกรมนักเรียน ไทยวัฒนาพานิช กทม, New Model English - Thai Dictionary. ISBN 974-08-3253-9 Thai calendar for August 2004, web dictionary Thai-English English-Thai Thai Time by Anthony Diller Thai Buddha Images for the Days of the Week Thai Lunar/Solar Calendar

37.
Buddhist calendar
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While the calendars share a common lineage, they also have minor but important variations such as intercalation schedules, month names and numbering, use of cycles, etc. In Thailand, the name Buddhist Era is a numbering system shared by the traditional Thai lunisolar calendar. The Southeast Asian lunisolar calendars are based on an older version of the Hindu calendar. One major difference is that the Southeast Asian systems, unlike their Indian cousins, instead, they employ their versions of the Metonic cycle. However, since the Metonic cycle is not very accurate for sidereal years, yet no coordinated structural reforms of the lunisolar calendar have been undertaken. Today, the traditional Buddhist lunisolar calendar is used mainly for Theravada Buddhist festivals, the Thai Buddhist Era, a renumbered Gregorian calendar, is the official calendar in Thailand. The Burmese calendar in turn was based on the original Surya Siddhanta system of ancient India, one key difference with Indian systems is that the Burmese system has followed a variation of the Metonic cycle. It is unclear from where, when or how the Metonic system was introduced, the Burmese system, and indeed the Southeast Asian systems, thus use a strange combination of sidereal years from Indian calendar in combination with the Metonic cycle better for tropical years. In all Theravada traditions, the epochal year 0 date was the day in which the Buddha attained parinibbāna. However, not all agree on when it actually took place. In Burmese Buddhist tradition, it was 13 May 544 BCE, but in Thailand, it was 11 March 545 BCE, the date which the current Thai lunisolar and solar calendars use as the epochal date. In Myanmar, the difference between BE and CE can be 543 or 544 for CE dates, and 544 or 543 for BCE dates, in Sri Lanka, the difference between BE and CE is 544. The calendar recognizes two types of months, synodic month and sidereal month, the Synodic months are used to compose the years while the 27 lunar sidereal days, alongside the 12 signs of the zodiac, are used for astrological calculations. The days of the month are counted in two halves, waxing and waning, the 15th of the waxing is the civil full moon day. The civil new moon day is the last day of the month, because of the inaccuracy of the calendrical calculation systems, the mean and real New Moons rarely coincide. The mean New Moon often precedes the real New Moon, as the Synodic lunar month is approximately 29.5 days, the calendar uses alternating months of 29 and 30 days. Various regional versions of Chula Sakarat/Burmese calendar existed across various regions of mainland Southeast Asia, unlike Cambodian and Burmese systems, Kengtung, Lan Na, Lan Xang and Sukhothai systems refer to the months by numbers, not by names. The Buddhist calendar is a calendar in which the months are based on lunar months

38.
Anno Domini
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The terms anno Domini and before Christ are used to label or number years in the Julian and Gregorian calendars. The term anno Domini is Medieval Latin and means in the year of the Lord, There is no year zero in this scheme, so the year AD1 immediately follows the year 1 BC. This dating system was devised in 525 by Dionysius Exiguus of Scythia Minor, the Gregorian calendar is the most widely used calendar in the world today. Traditionally, English followed Latin usage by placing the AD abbreviation before the year number, however, BC is placed after the year number, which also preserves syntactic order. The abbreviation is widely used after the number of a century or millennium. Because BC is the English abbreviation for Before Christ, it is sometimes concluded that AD means After Death. However, this would mean that the approximate 33 years commonly associated with the life of Jesus would not be included in either of the BC, astronomical year numbering and ISO8601 avoid words or abbreviations related to Christianity, but use the same numbers for AD years. The Anno Domini dating system was devised in 525 by Dionysius Exiguus to enumerate the years in his Easter table. His system was to replace the Diocletian era that had used in an old Easter table because he did not wish to continue the memory of a tyrant who persecuted Christians. The last year of the old table, Diocletian 247, was followed by the first year of his table. Thus Dionysius implied that Jesus Incarnation occurred 525 years earlier, without stating the year during which his birth or conception occurred. Blackburn & Holford-Strevens briefly present arguments for 2 BC,1 BC, There were inaccuracies in the list of consuls There were confused summations of emperors regnal years It is not known how Dionysius established the year of Jesuss birth. It is convenient to initiate a calendar not from the day of an event. For example, the Islamic calendar begins not from the date of the Hegira, at the time, it was believed by some that the Resurrection and end of the world would occur 500 years after the birth of Jesus. The old Anno Mundi calendar theoretically commenced with the creation of the based on information in the Old Testament. It was believed that, based on the Anno Mundi calendar, Anno Mundi 6000 was thus equated with the resurrection and the end of the world but this date had already passed in the time of Dionysius. The Anglo-Saxon historian the Venerable Bede, who was familiar with the work of Dionysius Exiguus, used Anno Domini dating in his Ecclesiastical History of the English People, completed in 731. e. On the continent of Europe, Anno Domini was introduced as the era of choice of the Carolingian Renaissance by the English cleric and scholar Alcuin in the late eighth century

Easter, also called Pascha (Greek, Latin) or Resurrection Sunday, is a festival and holiday celebrating the …

Icon of the Resurrection, with Christ having kicked down the gates of Hades and pulling Adam and Eve out of the tombs. Christ is flanked by saints, and Satan—depicted as an old man—is bound and chained. (See Resurrection of Jesus in Christian art.)

The lunar phase or phase of the Moon is the shape of the directly sunlit portion of the Moon as seen from Earth. The …

Phases of the Moon, as seen looking southward from the northern hemisphere. The southern hemisphere will see each phase rotated through 180°. The upper part of the diagram is not to scale, as the Moon is much farther from the Earth than shown here.

A crescent moon above Earth's horizon is featured in this image photographed by an Expedition 24 crew member in 2010.

May–June 2005 calendar of lunar phases.

Image: Here is the obligatory " I gotta a new long lens" shot! (10746642215)